text: * by organic reduction at an electrode
  * by mild reducing agents such as ascorbic acid (vitamin C)
  * by gamma radiation from solvated electrons generated in water
  * photoinduced electron transfer
  * reduction by metal cations, most commonly a cuprous salt.
  * anion-induced dediazoniation: a counterion such as iodine gives electron transfer to the diazonium cation forming the aryl radical and an iodine radical
  * solvent-induced dediazoniation with solvent serving as electron donor